Nearly 50 Marine recruits at the San Diego Marine Corps Recruit Depot have tested positive for the novel coronavirus, as increased testing among their company revealed several had the virus despite showing no symptoms, the Marines said Wednesday.

The Union-Tribune first reported the outbreak among Bravo Company on April 14. The company of 237 has been quarantined at the Bachelor Enlisted Quarters on board the depot since April 11, according to Capt. Martin Harris, a depot spokesman.

Harris told the Union-Tribune Wednesday the spike in cases is attributable to the Marines’ new policy to test 100 percent of arriving recruits. The military’s understanding of the virus has evolved and adapted to the fact that many young people can have the virus yet present no symptoms.

In the days after Bravo Company arrived at the depot on March 30, a small number of recruits began showing symptoms of COVID-19. Initial close-contact testing revealed about 15 recruits had the virus, Harris said.

After 14 days in quarantine, the depot tested 100 percent of the platoon with the most cases for the virus. When more than 30 came back positive, the Marines decided to test the entire company.

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Results from those tests haven’t come in yet, but Harris said the Marines expect more will come back positive.

Bravo Company is the only company at the San Diego boot camp with confirmed cases of the virus, Harris said.

The ability of asymptomatic people to spread the virus has been called one of its “hidden powers” by the Navy’s surgeon general.

An outbreak on the San Diego-based aircraft carrier Theodore Roosevelt revealed about 50 percent of people who tested positive showed no symptoms of COVID-19. According to Harris, among the recruits at Bravo Company — who skew much younger than the carrier’s crew — that number is even higher.

The outbreak led to sweeping changes in how the Marines welcome new recruits to training.

On April 13, recruits from Echo Company arrived at the depot — the first company to arrive since Bravo two weeks prior. Instead of taking their places on the iconic yellow footprints that traditionally welcome new recruits, Echo Company was instead funneled to a base gymnasium, screened for fever and flu symptoms, and sent along to a San Diego hotel for a two-week quarantine.

All recruits from Echo Company were tested for the coronavirus Tuesday, Harris said. Results are expected Thursday.

Another new company — India Company — arrived in San Diego Monday and began their two-week quarantine. All recruits in India Company were tested for the coronavirus upon arrival and will be tested again at the end of quarantine, Harris said.

Harris said that increased social distancing measures and mask-wearing across the depot has led to a drop in seasonal flu and common cold cases that normally plague recruits living in close-quarters and engaged in intense training.

He said the Marines are confident that by quarantining new recruits the service will avoid another outbreak like the one involving Bravo Company. If Echo Company tests out of quarantine on time, recruits could finally take their places among those yellow footprints as soon as Friday.